Peritumoral deposits as an adverse prognostic indicator of colorectal cancer

BackgroundThe aim of this study was to determine the prognostic value of peritumoral deposits (PTDs) in colorectal cancer (CRC).MethodsA total of 695 patients with pT3/T4 CRC (1980 to 1999) were reviewed. Tumor deposits located ≥2 mm from the front of the direct spread in the primary tumor were evaluated as PTDs.ResultsPTDs were observed in 111 patients (16.0%). The incidence of PTDs increased according to increasing N stage: 7% for N0, 22% for N1, and 39% for N2 (P < .0001). Five-year disease-specific survival was 85.0% in patients without PTDs and 59.5% in those with PTDs (P < .0001). Multivariate analysis showed that PTDs affected disease-specific survival independent of T and N stages. A significant prognostic impact of PTDs was similarly observed in another cohort comprising 474 patients with pT3/T4 CRC (2000 to 2005). The κ values among 8 observers were .70 for PTDs and .32 for the conventional growth pattern.ConclusionsPTDs have considerable prognostic relevance and offer improved judgment reproducibility in assessing the invasive margin of CRC.